To enhance transport safety and efficiency, systems involving vehicle-to-vehicle communications, vehicle-to-infrastructure communications and/or infrastructure-to-vehicle communications, e.g. according to the standard ITS-G5, are becoming increasingly popular. In such systems, it is important that the communications are reliable, and that their implementation is cost effective.
Standards for such communications systems, such as said ITS-G5, often use relatively high carrier frequencies, e.g. around 5.9 GHz for ITS-G5. This means that the antenna placement has a significant impact on the quality of the transmission. Heavy vehicles are particularly challenging from this point of view, due to their shapes and dimensions, and finding a location for an antenna for the system, which provides a good transmission quality in a variety of situations, may be very difficult. Signals are especially blocked backwards as a trailer may obscure the line of sight. Blocked signals lead to lost information, which in turn leads to delays and increased uncertainty in applications of systems of said kind.
WO2012/084844 discloses a vehicle antenna system, e.g. for vehicle-to vehicle communication, with antennas placed in the external mirrors of the vehicle. However, this is a solution which is expensive to implement, since it adds complexity to the rear view mirrors, including antennas, adapters and RF cables. In addition, rear view mirrors are a vulnerable part of a vehicle, which may easily be damaged and need replacement. The inclusion of communications hardware in the rear view mirrors will thus increase costs both at vehicle production, and maintenance.
U.S. Pat. No. 4,210,357 discloses a radar antenna reflector located in a frame for a rear view mirror, and spaced rearwards from the mirror. However, this solution also adds complexity and cost to the rear view mirror, adding the reflector which needs to be provided with a special structure which transmits light rays but reflects radar frequency waves.